A wheel bearing used at an axle of a vehicle enables a vehicle wheel to rotate smoothly without frictional loss and connects the vehicle wheel to a vehicle body.
Referring to FIG. 1, a cross-sectional view of a conventional wheel bearing and a constant velocity joint assembled with each other is shown in FIG. 1.
As shown in FIG. 1, the conventional wheel bearing includes a wheel hub 4, an inner ring 3 press-fitted onto the wheel hub 4, an outer ring 5 disposed at a radial exterior of the inner ring 3, and rolling elements 2 provided between the inner ring 3 and the outer ring 5. In addition, a shaft of the constant velocity joint (CVJ) 6 is splined to an interior circumference of the wheel hub 4.
As shown in FIG. 1, disengagement of the constant velocity joint 6 in an axial direction is prevented by splining the shaft of the constant velocity joint 6 into the interior circumference of the wheel hub 4 and engaging a nut to an end 7 of the shaft in the wheel bearing.
According to the conventional art, as shown in FIG. 1, preload applied to the wheel bearing is maintained by plastically deforming an end of the wheel hub 4 through orbital forming process after the inner ring 3 is press-fitted onto an end portion of the wheel hub 4.
The preload means load applied to the wheel bearing in the axial direction through the wheel hub, the rolling elements, the outer ring and the inner ring. Life of the wheel bearing is greatly affected by the suitable preload.
If plastic deformation occurs through the orbital forming process, however, deformation of the inner ring 3 may also occur due to high load and distribution of a gap and quality may be enlarged.
In addition, clearance exists between a spline formed on an interior circumference of the wheel hub 4 and a spline 1 formed on an exterior circumference of the shaft when the wheel hub 4 and the shaft of the constant velocity joint 6 are splined to each other according to the conventional art. If load generated when the vehicle runs is applied to the wheel hub 4, the clearance becomes large and noise may occur.
In addition, since driving torque is transmitted only through spline coupling of the wheel hub 4 and the shaft of the constant velocity joint 6 according to the conventional art, it is hard to transmit the driving torque stably and great load is applied to the splines 1. Therefore, the clearance enlarges at engaging portion of the splines 1, durability may be deteriorated, and life is shortened.